Sorting out fault prone fuses - uses thermal treatment without electric load similar to operating conditions at rated fuse load

摘要

The fault prone fine fuses are sorted out at final production check by a process using heat treatment. The fuses have spring tensioned wire ends, connected with a melting solder during fuse blowing. For a given time period the fuses are exposed to a testing temperature without electric load, the temperature being of the order of operating temperature at rated load of the fuse. Preferably the time period covers several hours and the temperature ranges from 100 to 105 deg.C. The temperature may be 40 to 60 deg.C below the solder melting temperature, or 20 to 35 deg.C below the solder softening point. During testing the temperature may be periodically varied between the testing temperature and a considerably lower one, such as room temperature.